FMS Closes connections and rejects new connections

Hello,

I have been running FMIS 3.5 for about 18 months, and recently it started acting up even though I have not made any changes.  After a while (sometimes days, sometimes hours), it starts rejecting new connections, but it allows existing connections to keep working.  If I refresh my app, then I can't reconnect.  The license I have is unlimited.  Can anyone shed some light into why this is doing this and what I can do to fix it?  Sometimes it happens when only a couple dozen people are online, and today it did it about 4 times with over 1500 people online.

Thanks,

Brandon